Our house has in floor hydronics heat. The bottom floor is now mostly tile and an open floor plan, but it is divided into 3 heat zones. I have often wondered whether that made any sense or not to divide it into the zones. So I now have 3 ARMstamps (11U37) monitoring indoor temperatures, 1 outside and one clamped into my heat zone controller.

And while it was not very cold last night, I was surprised my heater was running for 7 hours !?! A battery backup was always required, but shorting the 24VAC that long implies the battery has to be larger or low current operation will be needed.

This is part of my project to build my own thermostat for the bottom floor of the house. More details and sources in the forum.

After five days and through a good size Sierra storm, I have 6 days of data, running the 3 zones seperately. Below it shows outside temp (until something broke), indoor temp and then operation of the heating 3 zones.

And at the bottom there are some notes, about weather and also our cat-approved alternate heat source.